Add keyboard support for iOS and macOS under MoltenVK.

xcode/ios/DemoViewController.mm

@@ -21,12 +21,15 @@ const std::string VulkanExampleBase::getAssetPath() {
 @implementation DemoViewController {
     VulkanExample* _vulkanExample;
     CADisplayLink* _displayLink;
+    BOOL _viewHasAppeared;
 }
 
 /** Since this is a single-view app, init Vulkan when the view is loaded. */
 -(void) viewDidLoad {
 	[super viewDidLoad];
 
+    self.view.contentScaleFactor = UIScreen.mainScreen.nativeScale;
+
     _vulkanExample = new VulkanExample();
     _vulkanExample->initVulkan();
     _vulkanExample->setupWindow(self.view);
@@ -37,8 +40,24 @@ const std::string VulkanExampleBase::getAssetPath() {
     _displayLink = [CADisplayLink displayLinkWithTarget: self selector: @selector(renderFrame)];
     [_displayLink setFrameInterval: 60 / fps];
     [_displayLink addToRunLoop: NSRunLoop.currentRunLoop forMode: NSDefaultRunLoopMode];
+
+    // Setup tap gesture to toggle virtual keyboard
+    UITapGestureRecognizer* tapSelector = [[UITapGestureRecognizer alloc]
+                                           initWithTarget: self action: @selector(handleTapGesture:)];
+    tapSelector.numberOfTapsRequired = 1;
+    tapSelector.cancelsTouchesInView = YES;
+    [self.view addGestureRecognizer: tapSelector];
+
+    _viewHasAppeared = NO;
 }
 
+-(void) viewDidAppear: (BOOL) animated {
+    [super viewDidAppear: animated];
+    _viewHasAppeared = YES;
+}
+
+-(BOOL) canBecomeFirstResponder { return _viewHasAppeared; }
+
 -(void) renderFrame {
     _vulkanExample->renderFrame();
 }
@@ -48,6 +67,45 @@ const std::string VulkanExampleBase::getAssetPath() {
     [super dealloc];
 }
 
+// Toggle the display of the virtual keyboard
+-(void) toggleKeyboard {
+    if (self.isFirstResponder) {
+        [self resignFirstResponder];
+    } else {
+        [self becomeFirstResponder];
+    }
+}
+
+// Display and hide the keyboard by tapping on the view
+-(void) handleTapGesture: (UITapGestureRecognizer*) gestureRecognizer {
+    if (gestureRecognizer.state == UIGestureRecognizerStateEnded) {
+        [self toggleKeyboard];
+    }
+}
+
+// Handle keyboard input
+-(void) handleKeyboardInput: (unichar) keycode {
+    _vulkanExample->keyPressed(keycode);
+}
+
+
+#pragma mark UIKeyInput methods
+
+// Returns whether text is available
+-(BOOL) hasText { return YES; }
+
+// A key on the keyboard has been pressed.
+-(void) insertText: (NSString*) text {
+    unichar keycode = (text.length > 0) ? [text characterAtIndex: 0] : 0;
+    [self handleKeyboardInput: keycode];
+}
+
+// The delete backward key has been pressed.
+-(void) deleteBackward {
+    [self handleKeyboardInput: 0x33];
+}
+
+
 @end